The present invention is directed to a method and device for manufacturing a stranded unit whose stranded element each consists of at least one light waveguide surrounded by a sheath and are twisted in alternate directions to form a bundle with an "SZ" pattern which bundle is covered by an outer jacket.
When cabling individual elements into a bundle, a danger, which is that the ends of the bundles will become unraveled, always is present. When the individual elements are combined into an "SZ" pattern of the so-called "SZ" cabling method wherein the elements are alternately twisted in two directions, this danger exists along the entire length of the cable because of the reversing locations or points, which is where the twist direction is changed, can be viewed as the ends of each stranded bundle.
It is known from German O.S. No. 27 23 659 to secure optical communication cables in their stranded state by means of spinning a retaining spiral over the cable and particularly in the direct proximity of the stranding or reversing points. Since the retaining spirals must be seated more or less firmly at least to a certain degree on the individual, cushioned light waveguides, a danger, however, exists that the fibers will be mechanically stressed in the undesirable manner.
The method for manufacturing cables and lines with stranded elements laid in a "SZ" pattern is known from the German O.S. No. 27 35 476, which discloses that the elements are alternately stranded or twisted with a left-hand twist referred to as a "S" twist and then a right-hand twist referred to as a "Z" twist. The German O.S. also discloses a special measure which prevents unraveling. In detail, this is carried out in such a manner by an auxiliary outlet in the form of a disk being provided following the "SZ" cabling device and by the auxiliary outlet being followed by an extruder which coats the stranded elements with a synthetic covering. Since a danger exists that the force causing the unraveling will press the synthetic covering, which is still soft, radially outward as the covering leaves the output of the extruder, a supporting tubular passage is provided at the outlet of the extruder. The inside diameter of this passage is matched to the outside diameter of the extruded jacket or covering and this passage is water cooled. This water cooled passage is then followed by a water cooling basin so that the unraveling of the elements is largely prevented. Thus, in this embodiment, the jacket, which has already been extruded on the bundle of twisted elements, is conducted in a tube that forms the supporting passage.